| /* |
| * Copyright 2017 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| #ifndef GrBackendTextureImageGenerator_DEFINED |
| #define GrBackendTextureImageGenerator_DEFINED |
| |
| #include "SkImageGenerator.h" |
| |
| #include "GrBackendSurface.h" |
| #include "SkMutex.h" |
| |
| class GrSemaphore; |
| |
| /* |
| * This ImageGenerator is used to wrap a texture in one GrContext and can then be used as a source |
| * in another GrContext. It holds onto a semaphore which the producing GrContext will signal and the |
| * consuming GrContext will wait on before using the texture. Only one GrContext can ever be used |
| * as a consumer (this is mostly because Vulkan can't allow multiple things to wait on the same |
| * semaphore). |
| * |
| * In practice, this capability is used by clients to create backend-specific texture resources in |
| * one thread (with, say, GrContext-A) and then ship them over to another GrContext (say, |
| * GrContext-B) which will then use the texture as a source for draws. GrContext-A uses the |
| * semaphore to notify GrContext-B when the shared texture is ready to use. |
| */ |
| class GrBackendTextureImageGenerator : public SkImageGenerator { |
| public: |
| static std::unique_ptr<SkImageGenerator> Make(sk_sp<GrTexture>, GrSurfaceOrigin, |
| sk_sp<GrSemaphore>, SkColorType, |
| SkAlphaType, sk_sp<SkColorSpace>); |
| |
| ~GrBackendTextureImageGenerator() override; |
| |
| protected: |
| // NOTE: We would like to validate that the owning context hasn't been abandoned, but we can't |
| // do that safely (we might be on another thread). So assume everything is fine. |
| bool onIsValid(GrContext*) const override { return true; } |
| |
| TexGenType onCanGenerateTexture() const override { return TexGenType::kCheap; } |
| sk_sp<GrTextureProxy> onGenerateTexture(GrContext*, const SkImageInfo&, const SkIPoint&, |
| bool willNeedMipMaps) override; |
| |
| private: |
| GrBackendTextureImageGenerator(const SkImageInfo& info, GrTexture*, GrSurfaceOrigin, |
| uint32_t owningContextID, sk_sp<GrSemaphore>, |
| const GrBackendTexture&); |
| |
| static void ReleaseRefHelper_TextureReleaseProc(void* ctx); |
| |
| class RefHelper : public SkRefCnt { |
| public: |
| RefHelper(GrTexture* texture, uint32_t owningContextID) |
| : fOriginalTexture(texture) |
| , fOwningContextID(owningContextID) |
| , fBorrowedTexture(nullptr) |
| , fBorrowingContextReleaseProc(nullptr) |
| , fBorrowingContextID(SK_InvalidGenID) {} |
| |
| ~RefHelper(); |
| |
| GrTexture* fOriginalTexture; |
| uint32_t fOwningContextID; |
| |
| // There is never a ref associated with this pointer. We rely on our atomic bookkeeping |
| // with the context ID to know when this pointer is valid and safe to use. This lets us |
| // avoid releasing a ref from another thread, or get into races during context shutdown. |
| GrTexture* fBorrowedTexture; |
| // For the same reason as the fBorrowedTexture, there is no ref associated with this |
| // pointer. The fBorrowingContextReleaseProc is used to make sure all uses of the wrapped |
| // texture are finished on the borrowing context before we open this back up to other |
| // contexts. In general a ref to this release proc is owned by all proxies and gpu uses of |
| // the backend texture. |
| GrReleaseProcHelper* fBorrowingContextReleaseProc; |
| uint32_t fBorrowingContextID; |
| }; |
| |
| RefHelper* fRefHelper; |
| // This Mutex is used to guard the borrowing of the texture to one GrContext at a time as well |
| // as the creation of the fBorrowingContextReleaseProc. The latter happening if two threads with |
| // the same consuming GrContext try to generate a texture at the same time. |
| SkMutex fBorrowingMutex; |
| |
| sk_sp<GrSemaphore> fSemaphore; |
| |
| GrBackendTexture fBackendTexture; |
| GrPixelConfig fConfig; |
| GrSurfaceOrigin fSurfaceOrigin; |
| |
| typedef SkImageGenerator INHERITED; |
| }; |
| #endif // GrBackendTextureImageGenerator_DEFINED |